Orchestral brass and fanfare - analysis of system


The question is - where do the elements of great brass reproduction reside in a system? In the story below, I think performance is limited by either my amp or tweeter. What do you think?

And now my story ...
My system at present:

Electrocompaniet EMC1 CDP with MKII upgrade
Pass Labs X-1 Pre
Krell KAV250a amp
B&W Nautilus 805s
Audioquest interconnect
Discovery speaker cable.

What I hear from individual solo brass instruments:
Lyrical sound with good harmonics and good "Pratt".
Equally good with coronets, flugels, trombones, baritones;
french horns may be a little compressed - but then that is their natural sound. Works equally well on loud and soft passages.

What I hear from symphonic brass in fanfare is different:
[e.g. Copland - new world symphony ]The "Pratt" is still there, mids and lows are good, however the highs become compressed at LOUD volumes. On low volume passages the system relaxes into my comfort zone again.

My own thoughts:

1. Is this the sound of clipping?
2. Is this the metal tweeter on the 805s?
3. Is this amp unable to open up the speakers enough?
(Krell generally has plenty of headroom - even the KAVs)
4. Have I hit the wall with what my speakers can do?
judit
Judit, put a Rowland Model 10 on your list of amps to try out. I am a brass freak, having played trombone for many years, and this is an amp that gets brass reproduction right. For me, the acid test is jazz big-band at high volume. The Model 10 still sounds clean at high volumes where a lot of other SS amps don't.

Also, you may want to look into speakers with soft-dome tweeters. Metal domes have resonances that seem to be excited by brass instruments more than other types which makes them sound harsh.

As someone else mentioned, the room is probably also being overloaded. So, to get the sound you want, you may need to address several things. Each contributes to the whole.
A final note (short this time). You may want to try a Symphonic Line Kraft 250 classA. It's one of the best machines I've heard for driving speakers full range (Nautilus). In your case the sub will make things even easier...
The limit on most systems *is* the tweeter. In general the speakers are guilty of *most* of the non-linear distortion - which increases with level no matter what. After that the worst offender is the amp. Most amps have problems in the power supplies where the rail voltages downward modulate on creshendi, and this causes a sort of distortion. Usually it is heard as a reduction in definition and space. Most noticeable on BIG choral pieces (try Dorian...) adding big brass instruments makes most amp/speakers go all to hell.

You can check this to some extent by dropping the levels about 10dB on playback and letting your hearing threshold recover adequately (read: wear earplugs for an hour) before listening.

All this *assumes* that the basic sound of the rest of the signal chain is not "challenged" and sounds pristine (big assumption).

This also assumes that your room *is* as previously mentioned not being overpowered and does not have a nasty problem with HF standing waves...

That relates to your playback level too. MOST home speakers will NOT go much louder than about 100 - 109dB range. EVEN at those levels there is significant added IM and THD. So,
you need to keep in mind that your peaks could exceed the output capabilities of both your amps and your speakers, depending upon what the average level you chose to listen at is. Which is one reason that some of the larger speakers, line source speakers and horn speakers offer some advantages in this department. (it's all yin/yang no matter what..)

_-_-bear